This invention generally relates to surgical instruments; and more particularly, the invention relates to trocar devices for providing communication to the abdominal cavity. Trocar devices in accordance with the present invention include a substantially reinforced obturator shaft which adds rigidity to overcome unwanted deflection during penetration.
A trocar is a surgical instrument that is used to gain access to the abdominal cavity. A trocar generally comprises two major components, a cannula and an obturator. In order to penetrate the skin, a small incision is made by the surgeon where the trocar is to be inserted. The distal end of the trocar is then inserted into the tissue. The obturator has a point or cutting edge at its distal end. By applying pressure against the proximal end of the obturator, the point is forced through the tissue until it enters a target location, such as the abdominal cavity. The cannula is inserted through the perforation made by the obturator and the obturator is withdrawn, leaving the cannula as an access to the abdominal cavity.
Because trocars included sharp blades, inadvertent tissue or organ puncture was a concern. One of the first technical challenges in connection with the design and manufacture of the trocar was the incorporation of features to enhance safety. Specifically, it was important to develop a safety trocar which could substantially lessen the possibility of unintentional tissue or organ puncture. A trocar which includes a safety shield on the obturator was developed to lessen the possibility of unintentional puncture. The shield is biased in an extended position to cover the penetrating tip of the obturator. When the surgeon desires to penetrate tissue with the trocar, the safety shield retracts and exposes the penetrating tip. The shield remains in the retracted position so long as pressure is continuously applied. When the surgeon fully punctures the body wall, the pressure is relieved and the safety shield returns to its extended position covering the penetrating tip. Therefore, inadvertent puncture of bodily tissue and organs within the body cavity can be avoided. An example of a trocar having a safety shield is disclosed in U.S. Pat. No. 5,709,671 issued to Stephens et al. on Jan. 20, 1998, which is hereby incorporated herein by reference.
While numerous trocars have been designed to prevent inadvertent puncture, there was still clearly room for improvement. Regardless of the safety mechanisms built into these instruments, there were concerns of accidental puncture to body organs. Therefore, other mechanisms for protecting tissues and organs from inadvertent puncture during surgery were developed. One such development in the design of trocars relates to the incorporation of visualization concurrently with penetration. An example of a patent which discloses a surgical penetration instrument adapted for visualization during penetration is U.S. Pat. No. 5,271,380 issued to Riek, et al. on issued Dec. 21, 1993, which is hereby incorporated herein by reference. This patent describes a penetrating instrument including a hollow, cylindrical sleeve and an imaging element attached to the sleeve at its distal end. In a preferred embodiment, it has a conical non-bladed penetrating tip to facilitate the advancement of the instrument into body tissue. The non-bladed obturator separates rather than cuts tissue while penetrating to gain access to a body cavity. In this way, the incorporation of a safety shield or another mechanism to protect tissue or organs from inadvertent puncture during insertion is unnecessary.
The advancement of the optical non-bladed obturator reduced safety concerns and inadvertent tissue punctures encountered with early trocars; however, there was still opportunity for improvement. The trocars in the prior art are constructed of a large number of elements requiring various techniques in assembling the optical non-bladed obturator, creating manufacturing challenges. For example, manufacturers assemble the obturator by gluing the penetrating tip on the shaft of the obturator, or by using other mechanical means known in the art. Not only is the large number of elements a challenge to assemble, there is also a significant cost associated with assembling all of these elements.
Many of the surgeons using the optical non-bladed obturator began using it without the aid of the imaging device. The surgeons found that they were comfortable performing the surgical procedures using tactile feed back.
This surgical preference and the desire to reduce manufacturing challenges and costs led to the development of a one-piece solid plastic non-bladed obturator. The one-piece solid plastic non-bladed obturator enabled the use of conventional plastic processing methods such as injection molding, thus reducing manufacturing and assembly costs. Using injection molding, the one-piece solid plastic obturator had a straight injected molded plastic shaft. However, tests showed that the force required to penetrate tissue was great enough to cause unwanted deflection of the molded obturator shaft, especially on small diameter devices. This flexibility would be problematic during tissue penetration. This invention overcomes the obturator shaft deflection problem.
In accordance with the present invention there is provided an obturator for penetrating body tissue which contains a handle and a shaft. The shaft has a proximal end attached to the handle and a distal end extending from it. The handle and shaft are formed from a single piece of molded polymer. A substantially rigid reinforcing member which is formed from a material having a greater rigidity than the molded polymer is disposed along the shaft.